Re: [PATCH 01/20] make sure that DNAME_INLINE_LEN is a multiple of word size

Jan Kara
2025-01-10T09:22:06Z

On Fri 10-01-25 02:42:44, Al Viro wrote:
> ... calling the number of words DNAME_INLINE_WORDS.
>
> The next step will be to have a structure to hold inline name arrays
> (both in dentry and in name_snapshot) and use that to alias the
> existing arrays of unsigned char there. That will allow both
> full-structure copies and convenient word-by-word accesses.
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/dcache.c | 4 +---
> include/linux/dcache.h | 8 +++++---
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index b4d5e9e1e43d..ea0f0bea511b 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -2748,9 +2748,7 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
> /*
> * Both are internal.
> */
> - unsigned int i;
> - BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
> - for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
> + for (int i = 0; i < DNAME_INLINE_WORDS; i++) {
> swap(((long *) &dentry->d_iname)[i],
> ((long *) &target->d_iname)[i]);
> }
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index bff956f7b2b9..42dd89beaf4e 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -68,15 +68,17 @@ extern const struct qstr dotdot_name;
> * large memory footprint increase).
> */
> #ifdef CONFIG_64BIT
> -# define DNAME_INLINE_LEN 40 /* 192 bytes */
> +# define DNAME_INLINE_WORDS 5 /* 192 bytes */
> #else
> # ifdef CONFIG_SMP
> -# define DNAME_INLINE_LEN 36 /* 128 bytes */
> +# define DNAME_INLINE_WORDS 9 /* 128 bytes */
> # else
> -# define DNAME_INLINE_LEN 44 /* 128 bytes */
> +# define DNAME_INLINE_WORDS 11 /* 128 bytes */
> # endif
> #endif
>
> +#define DNAME_INLINE_LEN (DNAME_INLINE_WORDS*sizeof(unsigned long))
> +
> #define d_lock d_lockref.lock
>
> struct dentry {
> --
> 2.39.5
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR